1. Field of the Invention
The present invention is directed to wastewater treatment systems methods, and in certain aspects, to systems for separating oil, water and solids in production fluids of oil and gas wells. In other aspects, the present invention is directed to systems for treating wastewater from petroleum refineries and chemical manufacturing facilities.
2. Description of Related Art
Stringent water quality standards impact the operations of petroleum production facilities. In certain of these operations increased feed stock throughput rates have resulted in more product being lost in wastewater streams.
In certain prior art systems, oil and gas production units pump fluid from below the earth's surface from a hydrocarbon bearing formation. The fluid typically is a mixture of oil, water, gases, and solids (e.g. sand or rock). The mixture then is separated first to recover or remove gases using, e.g., a pressure separator, either of a high or low pressure design. Once the gases are removed, a resulting liquid/solid phase is pumped through an oil-water separator. In certain aspects such a separator is basically a settling tank equipped with baffles designed to promote the separation of oil from the water and solids. Oil is removed from the top of the tank while water and solids are pumped from the bottom. The degree of efficiency to which the oil-water separator operates affects the amount of oil remaining in the water-solids portion. The water and solids may be disposed of together by deep well injection or are segregated if other disposal options are required.
Efforts are made in certain prior art systems to isolate refinery and petrochemical process wastewater from desired petroleum or chemical compounds. Such wastewater is collected and treated prior to disposal. Solids removed from the wastewater system (which may include tanks, sumps, and flow lines) must be treated according to governing waste regulations. Certain of these solids are hazardous wastes as defined by the U.S. Environmental Protection Agency. In certain aspects when the process wastewater enters a sump system it is pumped to an API separator which is similar in design to the settling tank used in the oil production field described above. Recovered oil is skimmed off the top of the separator while water is removed from the middle section and a sludge-solids mixture is pumped off the bottom. The recovered oil, called slop oil, is pumped to the slop oil storage tank and later refined or otherwise reused in the process units. The wastewater is treated to remove contaminates, usually in a biological treatment plant, and discarded to the public waters under a government permit. The separator sludge, along with any solids removed from the wastewater storage system and sludge from a DAF (Dissolved Air Floatation Unit) in the wastewater treatment plant are typically hazardous wastes which are managed accordingly. Since separated fractions from the treated wastewater proceed to other units for further processing, the amount of allowable contamination is critical. Severe unit upsets, poor product quality, and excessive amount of wastes often are the result of an incomplete separation of oil, water and sludge in the separator process. This new invention greatly improves this separation process and will replace API separators and DAF units in refineries and petrochemical facilities.
There has long been a need for effective and efficient treatment and separation methods and systems for wastewater from refineries and petrochemical facilities, and, particularly for such methods and systems at the location of wastewater generation. There has long been a need for such systems and methods that produce reusable, recyclable material. There has long been a need for such systems and methods in which the production of hazardous waste is reduced or minimized. There has long been a need for such systems and methods with which levels of fouling contaminants are reduced.